1. Field of the Invention
This specification relates to a circuit breaker, and particularly, to a circuit breaker capable of increasing an amount of heat radiated without an increase in an amount of copper used.
2. Background of the Invention
In general, a circuit breaker is an apparatus for opening and closing a normal load of a circuit and blocking a fault current. For example, a vacuum circuit breaker may open and close a circuit and rapidly break a circuit by extinguishing arc, which is generated when blocking a fault current, within a vacuum interrupter. The vacuum circuit breaker may be installed together with a distributing board (switchboard), in which various electric devices including a breaker are placed and managed for operation or control of an electric power station and a substation, an operation of a motor and the like.
FIG. 1 is a perspective view showing an inside of a circuit breaker according to the related art, FIG. 2 is a sectional view of FIG. 1, FIG. 3 is an enlarged view showing a current carrying path when the circuit breaker of FIG. 2 is connected, and FIG. 4 is an enlarged view showing a main part of FIG. 3.
As shown in FIGS. 1 to 4, a circuit breaker according to the related art may include a cradle 10 having a plurality of terminals 12, and a breaker main body 20 having a plurality of terminal connectors connected to the terminals 12.
The plurality of terminals 12 may be disposed at a rear area of the cradle 10 in a moving direction of the breaker main body 20.
The terminals 12 may be provided per each phase (for example, U-phase, V-phase, W-phase) of an electric power source.
Each phase-based terminal 12 may include an upper terminal 13 and a lower terminal 14 connectable to a bus and a load, respectively, and spaced from each other in up and down directions.
The breaker main body 20 may include a plurality of terminal connectors 22 connected to the respective terminals 12, and a plurality of vacuum interrupters 50 connected to the phase-based terminal connectors 22, respectively, to open and close an electric power source.
A conveyer 60 which allows the breaker main body 20 to be relatively movable with respect to the cradle 10 may be disposed on a lower side of the breaker main body 20.
The conveyer 60 may be movable between a connected position that each terminal connector 22 is connected to the terminal 12 and a disconnected position that each terminal connector 12 is disconnected from the terminal 12.
Each of the vacuum interrupters 50 may include a vacuum container 51, a fixed contactor 53 fixed to the vacuum container 51, and a movable contactor 54 placed to be contactable with and separated from the fixed contactor 53.
Each of the terminal connectors 22 may include a conductor 25 having one end connected to the vacuum interrupter 50, and a contact member 40 located on the other end of the conductor 25 to be connected to the terminal 12 at the connected position of the breaker main body 20. Each conductor 25 may have a shape of rod having a circular or rectangular section.
Each contact member 40, as shown in FIG. 4, may include a plurality of fingers 41 radially disposed on the same circumference, and a plurality of spring members 43 disposed on a periphery of each finger 41 to inwardly press the finger 41 along a radial direction.
With the configuration, when the breaker main body 20 moves to the connected position, the terminal 12 of the cradle 10 may be inserted into the contact member 40 of each terminal connector 22. Accordingly, as shown in FIG. 3, electric power of the upper terminal 12 of the cradle 10 may be applied to the lower terminal 14 sequentially via the upper terminal connector 22, the vacuum interrupter 50 and the lower terminal connector 22.
In the meantime, at the connected position of the breaker main body 20, when a current starts to flow as the terminal 12 and the terminal connector 22 are connected to each other, heat may be generated on a current carrying path. Especially, an amount of heat generated on a contact area between the conductor 25 and the contact member 40 and between the fixed contactor 53 and the movable contactor 54 of the vacuum interrupter 50 may relatively increase. Here, since one end of each terminal connector 22 is connected to the contact member 40 and the other end thereof is connected (contactable) with the vacuum interrupter 50, relatively high heat may be generated.
However, in the related art circuit breaker, since the conductor 25 of each terminal connector 22 has a cylindrical shape or a polygonal shape, it has a relatively small surface area as compared with an amount of current (amount of heat generated). This may cause an insufficient exchange between heat and air (an insufficient amount of heat radiated in the air), resulting in an excessive increase in temperature of each terminal connector 22. In consideration of this problem, when a diameter or width of the conductor 25 increases, an amount of copper used may increase. This may cause an increase in a fabricating cost. With the increase in the amount of copper, an overall weight of the circuit breaker may increase and a conveying cost and/or installation cost may increase accordingly.